At 2am, Kim, a 25-year-old office worker, opens a site designed to look like a food delivery app, though he has no plan to order. He chooses menu items, drops them into a cart and simulates the experience of placing an order. “It somehow feels like I actually ordered something,” he said. Kim said the habit helps him resist late-night cravings. “There are many times when I crave food late at night but hold back to save money. It feels like a real delivery app, so I somehow keep looking at it,”...